System and method for robotic surgical intervention in a magnetic resonance imager

ABSTRACT

A system and method for image guided assisted medical procedures using modular units, such that a controller, under the direction of a computer and imaging device, can be utilized to drive and track low cost, purpose specific manipulators. The system utilizes modular actuators, self tracking, and linkages. The systems can be optimized at a low cost for most effectively performing surgical procedures, while reusing the more costly components of the system, e.g. the control, driving, and tracking systems. The system and method may utilize MRI real time guidance during the above procedures.

CROSS-REFERENCE

This application is a continuation application of U.S. non-provisionalapplication Ser. No. 12/873,152, filed Aug. 31, 2010, entitled “SYSTEMAND METHOD FOR ROBOTIC SURGICAL INTERVENTION IN A MAGNETIC RESONANCEIMAGER”, naming Gregory S. Fischer, Gregory A. Cole and Julie G.Pilitsis as the inventors, which claims priority to and the benefit ofU.S. provisional application No. 61/238,405, filed Aug. 31, 2009, thecontents of both of which are incorporated herein by reference.

FIELD OF INVENTION

The present teachings relate generally to the field of guidanceequipment and, more particularly, to equipment that is used to aid inthe accurate guidance of surgical tools and/or sensors to locations inthe human body.

BACKGROUND

While the field of image guided surgical robotic assistance is still inits infancy, it is expanding rapidly. The benefit of image guidedrobotically assisted surgery is fairly clear: the combination ofcomputer controlled precision movement and high resolution soft tissueimaging allows the surgeon to accomplish the procedural goals withminimized damage to surrounding tissue. There are many organizationsacross the globe developing imaging compatible systems of, thoughcurrently few are on the market. Most research facilities are eitherattempting to rebuild general purpose serial manipulators for imagingcompatibility, or developing single purpose units to perform a multitudeof tasks on a single area of the body.

Stereotactic neural intervention is a commonly practiced surgicalprocedure today. There are many treatments and operations that requirethe accurate targeting of, and intervention with, a specific area of thebrain which utilize stereotactic neural intervention. One common use ofthis procedure is Deep Brain Stimulation (DBS), which is often used forthe treatment of Parkinson's Disease.

Magnetic resonance imaging (MRI) compatible systems have been developed,though they typically manually driven, bulky and/or inconvenient to use.There are systems for specific procedures such as DBS therapy, thoughthose systems are inconvenient to use and/or lack accuracy due to thelack of real time image guidance.

DBS is a technique for influencing brain function through the use ofimplanted electrodes. Direct magnetic resonance (MR) image guidanceduring DBS insertion would provide many benefits; most significantly,interventional MRI can be used for planning, real-time monitoring oftissue deformation, insertion, and placement confirmation. The accuracyof standard stereotactic insertion is limited by registration errors andbrain movement during surgery. With real-time acquisition ofhigh-resolution MR images during insertion, probe placement can beconfirmed intraoperatively. Direct MR guidance has not taken holdbecause it is often confounded by a number of issues including: MRcompatibility of existing stereotactic surgery equipment and patientaccess in the scanner bore. The high resolution images required forneurosurgical planning and guidance require high-field MR (1.5-3T);thus, any system must be capable of working within the constraints of aclosed, long-bore diagnostic magnet. Currently, no technologicalsolution exists to assist MRI guided neurosurgical interventions in anaccurate, simple, and economical manner.

Currently, a typical DBS placement procedure is comprised of thefollowing events:

-   -   1. Patient arrives at hospital for pre-procedure MRI scan.    -   2. Surgeons analyze the patient's images, and produces a        surgical plan.    -   3. Patient returns to the hospital where a stereotactic surgical        frame is attached to the skull in the operating room.    -   4. A computed tomography (CT) scan is taken of the patient with        the frame to register the surgical plan to the frame.    -   5. The surgical frame is manually aligned and used to guide a        drill for drilling the burr holes to gain access to the cranial        cavity.    -   6. The surgical frame is used to guide the placement of        electrodes through the burr hole.    -   7. Some form of placement confirmation is utilized (often micro        electrode recordings, fluoroscopy, or computed tomography.)    -   8. Often the procedure is repeated for bilateral insertion of a        second electrode.    -   9. Patient is sent to recovery.

This process has been used for several decades, though tissuedeformation can cause registration errors between the preoperativeimages used to create the surgical plan, and the state of the patientsanatomy during the procedure. These errors can lead to a host ofnegative side effects including: reduced effectiveness of the DBSequipment, unwanted neurological changes (mood shift, chronic gambling),brain injury, brain hemorrhage, etc.

This procedure has several other drawbacks, such as the following:

-   -   during the time between when the surgical plan is generated and        the procedure occurs, there is a possibility of soft tissue        shift within the patient, causing inaccurate placement of        electrodes;    -   when the cerebrospinal fluid drains after the first burr hole is        drilled, there is another possibility of soft tissues shift;    -   for some applications of DBS, micro electrode recordings cannot        be used for placement confirmation due to a high possibility of        causing brain damage;    -   shifts in soft tissue increase the risk of a blood vessel being        moved into the surgical path, which could cause brain        hemorrhage; and    -   electrode insertion itself will cause tissue deformation as it        is being inserted into the operative area.

Therefore, it would be beneficial to have a superior system and methodfor performing a plurality of robotic surgical interventions utilizingreal-time MM imaging.

SUMMARY

The needs set forth herein as well as further and other needs andadvantages are addressed by the present embodiments, which illustratesolutions and advantages described below.

The system of the present invention is based on embodiments which usemodular units, such that a controller can be utilized to drive and tracklow cost, purpose specific manipulators. The system utilizes modularactuators, self tracking, and linkages constructed from, for example,but not limited to, hard image compatible plastics that are not ferromagnetic, although under other circumstances such as, where magneticsare not utilized, ferro magnetic material may be used. Therefore, thesystem can be optimized at a low cost for most effectively performing aplurality of individual surgical procedures, while reusing the morecostly components of the system, e.g. the control, driving, and trackingsystems.

In one embodiment the system comprises a manipulator linkage whichtargets DBS electrode placement and allows the procedure to be performedbased on interactively updated MRI images. Alternatively, the system maybe used to perform the procedure based almost entirely on pre operativeimages in a manner similar to the typical approach in the operatingroom. The system is a safe and reliable electrode placement assistantthat overcomes the difficulties of working in a closed high-field MRI.The objective of the system, but is not limited to, enables registeringand placing electrodes within the brain under image guidance with halfmillimeter accuracy. The system reduces procedure time, cost, andcomplications while improving effectiveness and availability.

The method of the present embodiment includes, but is not limited to,MRI-compatible self-positioning stereotactic surgical guidance thatbridges the gap between high resolution imaging modalities andinterventional procedures that utilize them for planning purposes.

Further embodiments are used to facilitate MRI guided insertion ofelectrodes for deep brain stimulation under live imaging. Theembodiments comprise a central controller or controller, and actuatedmanipulator or armature, and a user workstation. The controller of thesystem contains a computing unit that can process sensor informationfrom the actuated armature as well as generate driving signals tooperate the armatures' actuators. Additionally, the central control unitcommunicates with a user workstation which combines position informationfrom the armature with scanner images in order to register the armaturesposition within the imaging space, and allow the user to generateposition commands for the robotic manipulator.

The method for the design of all of these components has generated asystem which produces minimal degradation (that is, almost no visuallyidentifiably interference) on MRI image quality. The modular system isdesigned to be able to use a wide variety of procedure specificmechanism, with the same controller so that the mechanism can havenumerous, limited degrees of freedom and more of the system is precisionmechanically constrained. The workstation may register the position ofthe robotic manipulator relative to the scanner and the patient, atwhich point the operator may develop or import a surgical plan tointeract with the desired intervention points. Once the plan isdeveloped, the operator may perform the procedure under live orreal-time imaging guidance.

Thus, the embodiments provide for a modular system for image guidedrobotic assisted medical procedures. The embodiments of the systemcomprises a manipulator for a specific medical procedure, a controller,an imaging device and a computer. The controller of the system isconnected to the manipulator. The controller directs at least one motionof the manipulator. The controller is also capable of directing at leastone other manipulator. The imaging device of the system enablesvisualization of a tissue at the specific medical procedure. Thecomputer of the system is connected to the imaging device and thecontroller. The computer collects and processes images from the imagingdevice and instructs the controller to direct the manipulator. Thesystem of the present invention can also be used when the medicalprocedure is a surgical procedure. The surgical procedure can be, but isnot limited to, a deep brain stimulation procedure.

The embodiments also provide for a method for image guided roboticassisted medical procedures. The method comprises identifying an area ofa body for a medical procedure. The method also comprises defining atleast one motion of an instrument, this, at least one motion, isrequired for performing the medical procedure. The method furthercomprises assembling a manipulator which can be used for the medicalprocedure. Assembling of the manipulator comprises identifying linkagesfor performing the above at least one motion, and selecting actuatorsand sensors for connecting to the linkages. The actuators and sensorsare used for controlling movements of the linkages. The method evenfurther comprises connecting the manipulator to a controller which iscapable of directing the manipulator. The controller is also capable ofdirecting at least one other manipulator.

Other embodiments of the system and method are described in detail belowand are also part of the present teachings and can include work withvarious other body parts such as, but not limited to; prostates, lungs,breasts, hearts, limbs such as knees, hips and the like.

For a better understanding of the present embodiments, together withother and further aspects thereof, reference is made to the accompanyingdrawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B block diagrams illustrating a design of the systemarchitecture;

FIG. 2 is a flowchart illustrating a method of the system;

FIG. 3 is a flowchart illustrating a method of using the system;

FIG. 4 is a schematic diagram illustrating functional units comprisingthe controller of the system and their interconnects;

FIG. 5 is a schematic diagram of an embodiment of the system of thisinvention;

FIG. 6 is a schematic diagram of the components and connections of thecontroller;

FIGS. 7A and 7B illustrate the modular equipment rack design of theGausian cage for the controller without the feet shown;

FIG. 8 illustrates schematically the power converter of the controller;

FIG. 9 is a schematic diagram of the actuator drivers of the controller;

FIG. 10 is a schematic diagram of the power converter;

FIG. 11 is a schematic illustration depicting the kinetic equivalency ofthe eight-degree of freedom embodiment of the manipulator of the system;

FIG. 12A illustrates the three degrees of freedom 6, 7 and 8 of FIG. 11provided by the yolk of the manipulator;

FIG. 1214 illustrates the three degrees of freedom provided by aprismatic X-Y-Z-stage as the manipulator is used with a skull;

FIG. 13 is a schematic depiction of an embodiment of the manipulatorwith six degrees of freedom; and

FIG. 14 illustrates the basic system configuration of an embodiment ofthe present invention.

DETAILED DESCRIPTION

The present teachings are described more fully hereinafter withreference to the accompanying drawings, in which the present embodimentsare shown. The following description is presented for illustrativepurposes only and the present teachings should not be limited to theseembodiments. In addition, the publication entitled, “MRI CompatibilityEvaluation of a Piezoelectric Actuator System for a NeuralInterventional Robot,” authored by Yi Wang' Gregory A. Cole, Hao Su,Julie G. Pilitsis and Gregory Fischer, presented at the 31St AnnualInternational Conference of the IEEE EMBS, Minneapolis, Minn., USA,

Sep. 2-6, 2009 is incorporated in its entirety by reference.

Referring now to FIG. 1, shown is a block diagram depicting anembodiment of the system architecture. The system 100 comprises aworkstation 102, a controller 104, a robotic device or manipulator 106.Also shown is the clinical equipment or hospital equipment 108 that maycooperate with the system. The user workstation 102 serves as a planningand navigation workstation for the user. Workstation 102 may be, but isnot limited to, a laptop computer located in an MRI scanner's consoleroom. Alternatively, it may be a separate computer, integrated into themedical imaging equipment, or a part of a standalone system (not shown).Workstation 102 is communicative coupled via data connections orcouplings 110 and 112 to the robot controller 104 which, in oneembodiment, is located inside the MRI scanner room and coupled via fiberoptic communications. Alternatively, coupling 110 and 112 may be ashielded cable or wireless link. The workstation 102 sends commands andregistration to the robotic device or manipulator 106 via 110 andreceives robot status and location via connection 112. In oneembodiment, the controller 104 receives alternating current (AC) powerfrom the scanner room via a grounded cable 118. Alternatively, directcurrent (DC) power may be directly supplied or a battery may be used toprovide power. The physical manipulator 106 can be the robotic devicethat interacts with the patient. It typically is MRI compatible and sitsinside an MRI scanner bore while performing an intervention. Manipulator106 is coupled to controller 104 via information connectors or signals114 and 116. Connector 114 provides the robot controller 104 withinformation from the robot's sensors, including the position of thecontroller or manipulator 104. Connector 114 may be an electricalconnection containing one or more channels from, for example, an opticalencoder utilizing a differential signal output. Alternatively, it mayprovide a digital or analog digital from other encoder or potentiometer.Position sensing may alternatively be performed using fiber optics thatcommunicate along connection 114. Connection 114 may also includepressure, force, torque, or other sensory information. Connection 116provides control signals to the manipulator's actuators. In oneembodiment, connection 116 is a shielded electrical cable that providesa drive signal to piezoelectric motors. Alternatively, connection 116may transmit pneumatic or hydraulic power to the manipulator 106.Manipulator 106 performs the surgical intervention. In one embodiment,manipulator 106 is an actuated frame for assisting deep brainstimulation lead placement inside an MRI seamier. In one embodiment, themanipulator 106 is composed of two separable components, a motor moduleand an application-specific or patient-specific mechanism.

Hospital equipment 108 can include the medical imaging equipment. In oneembodiment, equipment 108 includes an MRI scanner. The MRI scannertransmits images via communication coupling 120 to the workstation 102.The workstation 102 can operate software which tracks a patient anatomyand generates the user interface overlaying the position of themanipulator 106. This workstation 102 is designed to contain all of thesoftware utilized to interface with the user and manages a large portionof the high power processing such as three dimensional image creationand analysis. The software facilitates interactions with the MRI scannerlocated in the equipment 108 and the controller 104 of the system 100.The workstation 102 may communicate with an image server located inhospital equipment 108 associated with the MRI so that images generatedby the scanner may be utilized by the navigation software. The imagesmay be transferred via a Digital Imaging and Communications in Medicine(DICOM) server, direct connection, real-time streaming, or other means.In one embodiment, the workstation 102 can also send commands to the MRIscanner to control scan parameters including, but not limited to, scanplane location, scan plane orientation, field of view, image update rateand resolution. The workstation 102 may first register the position ofthe robotic device or manipulator 106 relative to the patient or imagingsystem, at which point the operator may develop a surgical plan tointeract with the desired intervention points. Once the plan isdeveloped, the operator may perform the procedure under live imaging orreal-time guidance so that during the procedure the operator will beable to confirm that the intervention axis is oriented optimally forinsertion. Additionally, the operator will be able to confirm theplacement of surgical instruments at desired locations.

In one embodiment, the manipulator 106 is mechanically coupled to aplatform placed upon the bed of the MRI scanner, wherein the platformalso includes imaging coils and head fixation. In a further embodiment,the controller 104 also controls the orientation of the MRI imaging coilto align an opening with the planned robot trajectory. The imaging coilmay be controlled by the robot controller or controller 104 or by othermeans such that it may be reconfigured to optimize patient access whilemaintaining image quality. Further, the manipulator 106 and the platformmay also incorporate active or passive tracking fiducials or coils tolocalize the robot in the MRI scanner. In alternate embodiment, themanipulator 106 is coupled to a head frame and/or operating room tableand the controller 104 is also located in the operating room.

This system 100 of the present invention is, essentially, a highprecision, closed loop system that can be used to compile MRI imageslices into three dimensional images, overlay a three dimensional imageof a manipulator that can be operated within the scanner bore, select acourse of motion for an intervention, and execute the intervention underlive image guidance. While this has benefits in the medical world, thereare also benefits to other industries where the precision internalimages of the MRI can be utilized. Some of the industries used with thesystem can be instrumental and are, for example, art restoration, plantsplicing, and veterinary work. Additionally, while this system is MRIcompatible, it is also compatible with most other imaging modalitiescurrently utilized. As such, under other imaging modalities that do notrequire magnetic compatibility, this system could be utilized, forexample, by law enforcement, or manipulation of internal structures ofdevices.

The system 100 described herein has modular architecture. The system 100can be integrated into an MRI surgical suite. Individual surgeons orhospitals can use a variety of manipulators 106 or end effectors for themanipulator 106 for the specific procedures that they perform.Alternatively, custom patient-specific modules for the manipulators 106may be used with the system. A single controller 104 is capable ofoperating the variety of manipulators 106. This distributes the cost ofboth equipment and maintenance of the devices in a manner where“everyone just pays for what they use.” By distributing the paymentstructure, different institutions and individuals may be responsible fortheir own segments of equipment.

In another embodiment, although not limited thereto, the systemcomprises an MRI-compatible self-positioning surgical guide utilizing asimilar procedure planning to stereotactic intervention. This systembridges the gap between high resolution imaging modalities andinterventional procedures that utilize them for planning purposes. Thesystem may utilize live MRI guidance during these procedures. Alternateembodiments of the system may be used for applications other than deepbrain stimulation such as with other body parts such as prostrates,lungs, hearts, knees and the like. Other neurosurgical procedures may beperformed with the present invention including lead placement, thermaland cryogenic ablation, injections, evacuation, and surgicalinterventions. The invention is not restricted to only the specificallymentioned clinical applications. Further embodiments may be used toaccess other organ systems including for MRI image-guided prostatebrachytherapy, biopsy and ablation.

The system 100 allows the use of in situ MRI guidance during a neuralintervention procedure with the added benefit of computer controlledmotion for the positioning of a tool guide. In one embodiment, althoughnot limited thereto, the system 100 operates within the scanner bore ofa closed-bore, high-field, diagnostic MRI scanner. This device mayactively drive the position of the tool guide while leaving anacceptable volume of workspace for performance of the operation by thesurgeon. In order to accomplish this, the system 100 may utilize similarplanning methods to a manual stereotactic surgical procedure. Forinstance, although not limited thereto, system 100 may utilize amechanically constrained remote center of motion (RCM) style linkage,where the RCM point is placed within the cranial volume at the targetlocation. In such a way, the primary insertion axis of the devicetargets the RCM point no matter where the insertion guide is moved. Thisallows the operator to set a desired intervention point and insert toolsfrom an arbitrary burr hole location on the skull to reach the sametarget point. Alternatively, the RCM point may be placed in the moretraditional manner at the skull entry point and allow access to a rangeof target locations through the same burr hole.

The system 100 may also incorporate power transmission, although notlimited thereto, that permits the use of modular end effecters to expandthe functionality of the system 100 with two additional degrees offreedom (DOF) See FIG. 11. In one embodiment, the system uses anarmature that mounts to either side of the patient's skull and iscontained within a small volume in order to leave as much room aspossible within the scanner bore for the surgeon to move. The system mayalso be integrated with the tray that the patient rests on during theprocedure, although not limited thereto. The system may also beintegrated with the MR imaging coil, although not limited thereto.

The method of configuring the system 100 of the present invention isillustrated in FIG. 2. The configuration is defined by the medicalprocedure described in block 202 to be performed by the system 100. Thespecific procedure and/or patient configuration are used to determinethe requirements as described in 204. The requirements are used toselect or develop manipulator 106 or end effector as described in 206.The manipulator 106 or end effector 106 is coupled to the robotic systemand controller 104.

A method used in system 100 can be as follows:

-   -   1) identify the area of the body to be manipulated    -   2) identify motions required to perform procedure    -   3) analyze motions and forces    -   4) design manipulator to meet requirements    -   5) select and apply actuators    -   6) select and apply sensors and fiducial markers    -   7) analyze and insert kinematics of manipulator in software        system    -   8) once the manipulator is constructed and the kinematics are        inserted to the control software, the new manipulator can be        utilized.

The method of utilizing the system 100 of the present invention isillustrated in FIG. 3, in a flow diagram re-procedural imaging 302 isacquired prior to the intervention. Imaging 302 may include, but is notlimited to, anatomical MRI, functional MRI, spectroscopic imaging andcomputed tomography or the like. These images may be acquired days orweeks before the procedure, or may be performed the day or immediatelyprior to the intervention. Pre-procedural images 302 are used in medicalprocedure planning 304. The target or targets are identified 306. Thisstep may be manual, semi-automated, or fully automated. In oneembodiment, statistical atlases may be used to assist in locating thetarget location. A planned trajectory is also identified in 306. Thistrajectory may be manually generated or it may be generated in anautomated or semi-automated fashion. In one embodiment, blood vesselsand other critical structures are automatically located and a safetrajectory is planned. Once the procedure is defined, a patient isplaced within the bore of a diagnostic scanner. In an embodiment, thepatient is placed inside an MRI scanner along with the robotic device ormanipulator 106. A series of images are taken of the patient anatomythat the procedure needs to be performed on and used to register thepatient with eth pre-procedural plan. This step may also be repeatediteratively or continuously during the procedure. The images areassembled in the workstation 102 of FIG. 1 into a three-dimensionaldisplay where the physician can view and modify the medical plan.

The robotic manipulator 106 is localized within the scanner andregistered to the patient in 308. Localization may be performed byimaging fiducials, active tracking coils, an external tracking system orother means. The motion plan for the robot is generated based on therelative pose of the robot to the patient and the planned trajectory ortarget 306. The manipulator 106 is commanded to move and align thesurgical tool as described in 312. The surgical tool may be a needle,electrode, marker, drill, drill guide, cannula, ablation probe, laser,or other similar device. Real time or interactive medical images of themanipulator 106 and the patient may be performed during motion 312 toguide alignment. Position sensing on board the manipulator 106 orexternal to it may be used to guide for alignment. Upon completion ofmotion or at a stopping point in an iterative insertion, confirmationimages are acquired 314. If the tool is not yet at the target location,the plan is updated in 310 and the process is repeated or iterated. Inone embodiment, continuous MRI images are used for closed loop controlof an electrode, cannula or other instrument. Once placed, theinterventional procedure, or a current step within, is performed in 318.Placement is confirmed in 320 and the process may be iterated to ensureappropriate position as defined in 324. In one embodiment, confirmation320 is performed via micro electrode recordings. In an alternateembodiment, high resolution MRI imaging is utilized. In anotherembodiment, fluoroscopy or computed tomography imaging confirmsappropriate placement. In procedures with multiple stages, the processmay be repeated as shown in 322. This may be the result of multiplestages. In one embodiment, the manipulator guide alignment of a surgicaldrill to generate a burr hole in the skull and then later aligns a guidecannula and an electrode. The robot manipulator 106 may move in and outof position between stages to allow improved patient access. Further,the procedure may be repeated for multiple targets. When complete, themanipulator 106 retracts or is removed 326. Additional validation may beperformed to ensure a successful procedure 328 and the procedure iscompleted 330. For procedural planning, guidance and validation, the MRIimaging may include one or more of: traditional diagnostic imaging,rapid imaging, 3D imaging of arbitrary pose, volumetric imaging,functional imaging, spectroscopic imaging, blood flow sensing, diffusionimaging or other approach. Further, multi-modality imaging may beincorporated to couple MRI imaging with ultrasound or other medicalimaging means.

The configuration of one embodiment of system 100 of the presentinvention is illustrated in the block diagram of FIG. 4. Navigationsoftware 402 is located on workstation 102. The navigation software 402is used to guide the intervention and may also be used for preoperativeand intraoperative planning as described previously. In one embodiment,the navigation software 402 is based on the modular, open source 3DSlicer software. Alternatively, navigation software 402 may be acommercially developed platform. Navigation software 402 iscommunicative coupled to an MRI medical imaging system or interfacecomputer or interface 404. The communication interface may be anestablished protocol such as DICOM or OpenIGTLink. Alternate protocolsor connections may be utilized. The navigation software 402 may sendcontrol signals to the imaging system interface 404 to control scanplane location, orientation or other parameters. In one embodiment, theimaging continuously streams images to the navigation software 402 thatvisualizes them on workstation 102 of FIG. 1. Imaging system interface404 controls the MRI scanner or other imaging system 408 and retrievesplanar and volumetric image data from the scanner. The robot controller406 represents the controller 104 of FIG. 1. The controller 104 iscommunicatively coupled to the navigation software 402. In oneembodiment, the coupling is a fiber optic network connection. In anembodiment the navigation software 402 sends commands including, but notlimited to, positions, orientations, velocities, and/or forces to thecontroller 104. In an embodiment, the robot controller 104 incorporatesa control computer that receive the data from the navigation software402 and performs the necessary computations. The computations mayinclude one or more of forward kinematics, inverse kinematics,trajectory generation and registration. The robot controller 104 sendsdata to navigation software 402 including, but not limited, to themanipulator 106 position, orientation, workspace, and interactionforces.

In an embodiment, the manipulator 106 is actuated by piezoelectricmotors 412 and joint positions are sensed by optical encoders 414. Thepiezoelectric motors 412 are controlled by piezoelectric motor drivers410. In a further embodiment, the piezoelectric motor drivers 410 areconfigured to minimize interference with the MRI scanner 408 and mayinclude filtering. The motors 412 may be controlled to provide positioncontrol, speed control, or force control. Force control of thepiezoelectric actuators may be accomplished by varying the drivewaveform's amplitude, frequency, phase or other parameters to modify thefriction between the driven element and the motion generating elementsof motors 412. In an additional embodiment of the present invention therobotic manipulator 106 is teleoperated. In a further embodiment, hapticfeedback may be available. The robot controller 106 may communicatedirectly with the motor drivers 410, or there may be an intermediateinterface such as backplane with signal aggregator. In an embodiment,the piezoelectric motor drivers 410 and robot controller 406 arecontained in controller 104 which is enclosed in an EMI shieldedenclosure located in the MRI scanner room. In an alternate embodiment,the functionality of the robot controller 406 is integrated with thenavigation software 402, and the workstation 102 (see FIG. 1)communicates directly with the motor divers 410 or correspondinginterface. A modular system architecture allows the location of thebreaks between software and hardware components to be adapted to aspecific application.

A specific embodiment of system 100 of the present invention is shown inFIG. 5. In FIG. 5, the user workstation 502 represents workstation 102and includes a computer and a communication interface. In oneembodiment, the communication interface is, but not limited to, a fiberoptic Ethernet media converter. A set of coordinates for the endeffector of the manipulator 506 (also 106) are selected, and sent to thecontroller 504 (also 104). In one embodiment, the controller 504 isenclosed in a Faraday cage forming an electro-magnetic interference(EMI) shielded enclosure and contains an AC-DC power rectifier, one ormore low-noise, linear or low frequency switching DC-DC powerconverters, a control computer, actuator drivers with output filtering,sensor interfaces and a communication interface. The in-room controller504 represents controller 104 and uses the kinematic information aboutthe manipulator 506 (also 106) and the coordinate information togenerate a planned pose for the manipulator 506. The physicalmanipulator 506 represents the manipulator 106, wherein it incorporatesa task-specific end effector. The end effector may be in the form of alinkage mechanism. Further, the linkage mechanism itself may beunactuated and coupled to an actuator module to complete the manipulator506 or 106. The manipulator 506 or 106 may also include sensors andfiducial markers. The pose is then achieved through manipulation of theindividual actuators through drive signals 512 in a closed loop fashionutilizing sensor information 514 from the manipulator 506 itself. Oncethe controller 504 interprets that the manipulator 506 has reached theintended planned position, the workstation 502 utilizes a medicalimaging system to verify the position of the manipulator's end effector.The medical imaging system may incorporate one or more of an MRIscanner, patient table, imaging coils, DICOM or other imaging server,power source and air supply as described in 508, which represent thehospital equipment 108. The power source and air supply 518 may beconnected to the in-room robot controller 504. In one embodiment, thepower source is, but may not limited to, approximately 110 volt AC powerand a ground cable that is connected to the rectifier and DC-DCconverted within controller 504.

Now referring to FIG. 6, the inner workings of one embodiment of therobot controller 504/104 is described. The continuous Faraday cageenclosure 602 houses the entirety of the controller equipment. The patchpanel 604 acts to allow the passage of electrical and other forms ofinformation and energy to be passed in and out of the enclosure 602without allowing the escape of EMI. These connections include theoptical data transfer connection 624 which the control computer uses tocommunicate with the workstation 502 (or 102), as well as the controllersupply lines 616 and the actuator and sensor signals 626. The next pieceof equipment is the controller computer 606 which is generally a common,off the shelf computer capable of running the software required toperform the operation described in FIG. 3. This is generally implementedas a common, off the shelf computer with the power supply removed so itselectrical power can be supplied by the custom power converter 612. Thisdevice is connected via digital data connection to the signal aggregator608, which can include, but is not limited to Transmission ControlProtocol/Internet Protocol (TCP/IP), Universal Serial Bus (USB), OpenImage Guided Therapy Link (OpenIGTLink), or others. The signalaggregator 608 is a device that manages the passage of information fromthe control computer 606 to the actuator drivers 610, and back throughphysical or data connections 620 and 628. Additionally, the signalaggregator 608 combines the driving signal and sensor information linesfrom the actuator drivers 610 to the multiconductor connector in thepatch panel 604 via the multiconductor electrical data connection 626.Additionally, the media converter 614 communicates with the controlcomputer via electrical data connection 618, and converts the media toan optical data stream that is passed out of the patch panel 604 throughoptical connection 624. Finally, all electrical devices within theenclosure get their power from the power converter 612, which is builtlater to supply all the required DC voltages, and connected to allsupported equipment via the DC voltage rail connections 622.

Continuing to FIGS. 7A and 7B, which is a diagram of the continuousFaraday cage enclosure, surrounding the controller equipment, the basicstructure of this device is provided by the conductive paneling 710which can be made of many materials such as, for example, but is notlimited to, sheet aluminum, steel, or a non conductive material with aconductive coating. Cut into this sheeting is vent ports 704 which allowthe exchange of air for the purposes of cooling, which have EMIshielding vents mounted to them. Additionally cut into the structuralsheeting 710 is the port for the supply connection patch panel 708 (also604) where the different electrical and non-electrical supplies arepassed into the controller in a manner that shields EMI from escaping.These supplies can include, but are not limited to, AC wall current,compressed air, and DC voltage supplies. Additionally, cut into thestructural sheeting 710 is the port for the manipulator connector patchpanel 706 where the multi-element cables used to transfer drivingsignals and sensor information back and forth between the manipulatorand the controller box. These elements can include, but are not limitedto hydraulic, pneumatic, and electrical transfer lines. Finally, thecage FIG. 7A is completed with a lid 702 designed to be opened andclosed more frequently than the patch panels and thus contains an EMIshielding gasket.

Referring now to FIG. 8, a general view of the internal operation of anactuator driver is shown, beginning with the command input 802 from thepiezoelectric actuators which is fed into the signal processor 804. Thecommand input can be comprised of a variety of forms of analog anddigital data which may include, but is not limited to velocity,position, and force commands. The input 802 may be passed to the signalprocessor 804 via synchronous or asynchronous serial communication,Ethernet, USB, fiber optics, or other means. Driving signals are thenproduced and amplified in the signal generation segment 808, which canbe comprised of but is not limited to, a series of operationalamplifiers connected to the output of a digital to analog converter thatreceives the digital information from the signal processing unit orsignal processor 804. The output of the signal generation segment 808 isthen passed into the filtering stage 810 which is used to blockbandwidths of electrical signals which may be in frequency ranges thatcause unfavorable image distortion. The output of the filtering stage810 is then sent to the piezoelectric actuators 802 via themulti-element shielded cable coming from the faraday cage 602 patchpanel 604. The cables may terminate in a shielded breakout board on ornear the manipulator 106 or connect directly to the actuators.

Now referring to FIG. 9, the detailed internal function of oneembodiment of the piezoelectric actuator driver 610. Initially commandinformation 802 is passed from the signal aggregator 912 via the serialdata connection 926 to the microcontroller 902. The microcontroller 902in this embodiment has the function of handling communications with theaggregator 912, and control of the signal generator and sensinginformation. The microcontroller 902 communicates with the FPGA 904 viaposition data connection 914, as well as the volatile memory 906 viadata connection (wavetables) 922. Data connection 922 where the data isin the form of waveform tables that are produced in analog form to drivepiezoelectric actuators 804. The field programmable gate array (FPGA)904, where the FPGA 904 is used to pull waveform information from thevolatile memory 906 and use it to execute commands received overposition data connection 914. Where FPGA 904 is also used to receivesensor information over position sensor signals 928 to be used forpurposes including, but not limited to, execution of said commandsreceived from microcontroller 902. Where the parallel data stream 916produced by the FPGA 904 is then interpreted into analog actuatordrawing signals 920, by first converting them into a low voltage analogwaveform Connector 918 by the digital to analog converter (DAC) andpreamplifier 908. The preamplifier 908, which can be comprised of, butis not limited to, high speed parallel digital to analog converterswhich can convert the digital waveform information stored in volatilememory 906. Once the low voltage analog driver signal. 918 is produced,it is then amplified and filtered by the output stage 910 which iscapable of multiplying the voltage and supplying a high amount ofcurrent. Components in this stage are over-specced in order to preventnoise.

Referring now to FIG. 10, the power converter 612 as shown in FIG. 6 issupplied by the patch panel 604 via the AC input 1002. The AC input 1002is carried by the wall current connector 1008 which is of the form of acable rated to handle the electrical load required to operate the restof the electrical equipment. This AC current is passed into the bridgerectifier 1004 where the voltage is divided before rectification toapproximate the highest DC voltage required by the system. There is thena large capacitive filter pre and post rectification or full phaserecited voltage 1010 in the rectifier 1004 to prevent rejection of noiseback through the supply line and passing of noise to the converters.Once the input line is fully rectified and filtered 1006, it is thenpassed through the programmable buck converters 1006. Programmableconverters are utilized so that the switching frequency can becontrolled to prevent image degradation. Finally the DC voltage rails orsupplies 1012 are passed out of the custom power converter 612 ofsignals via connection

Referring now to FIG. 11 and FIGS. 12A and 12B, the kinematics of oneembodiment of the manipulator 106 as per its design for use assistingwith DBS electrode implantation. The first, second and third degree offreedom (DOE) are all contained within what is commonly called aprismatic XYZ stage labeled as the three DOF Translation Base 1102. Thenext two degrees of freedom are expressed as a two DOF remote center ofmotion style linkage 1104, where the RCM linkage can be described as,but is not limited to, mimicking the motion of a stereotactic neuralinsertion frame. The next two degrees of freedom are expressed as anoptional yoke 1106 and increases 6 degrees of freedom to 8 degrees offreedom that can be used to achieve insertion angles other than thosealong the RCM axis. This allows the manipulator 106 to achieve greaterdegrees of dexterity. The final axis which is, but is not limited to, apassive insertion axis 1108, where the surgeon may manually insert anelectrode. FIG. 11B and 11C show pictorially how the manipulator allowsfor 8 degrees of freedom and can be used with a skull in a DBS electrodeimplementation. The design is not restricted to six or eight DOF,alternate embodiments may encompass other numbers of degrees of freedom.Alternate specific applications will result in alternate mechanismdesigns.

Referring now to FIG. 12A and 12B, the manipulator 106 described earlierin a specific embodiment of said manipulator 106 adapted for DBSelectrode insertion. The manipulator 106 can be constructed of rigidplastic links 1208 pin jointed 1202 via non conductive rods with plasticsleeve bearings 1205 as shown in FIG. 13 and may be used at all pinjoint locations. The RCM point 1204 is clearly shown, and is targetedthrough all positions of the manipulator sweep 1207-1211 allowing asingle target point 1204 to be reached from multiple insertion angles1207, 1209, 1211 shown in FIG. 13 represents three manipulatorconfigurations overlaid to demonstrate the mechanically constrainedrotation center concept generated by motions 1104. This mimics themotion of a standard stereotactic insertion frame. The rotation centermay be placed at or near the target or it may be placed at or near theskull entry point. Additional dexterity afforded by the extra degrees offreedom of yolk 1106 enables repositioning of the rotation center thoughsoftware control. The 3 DOF translation base can be used to change theposition of the remote center of motion point. An enlarged view of FIG.11B is shown and FIG. 13 to show the extra DOF 6 and 7.

The configuration of a specific embodiment of system 100 of the presentinvention is shown in FIG. 14. Patient 1402 is placed inside MRI scanner1404 located in MRI scanner room 1400 and rests upon scanner bed 1406.Patient's head 1408 rests upon an integrated head rest platform 1412.Head fixation 1414 maintains head position relative to the platform1412. MRI imaging coil 1418 is coupled to platform 1412. In oneembodiment imaging coil 1418 is a standard head coil, surface coils, orother readily available imaging coil. Alternatively, imaging coil 1418may be specific for this system. In one embodiment, the imaging coil1418 is actuated and reconfigurable. Robot base 1420 is fixed toplatform 1412. Manipulator 1422 (also 106) sits upon platform 1412. Inone embodiment, robot base 1420 is a prismatic motion stage forpositioning and the manipulator 106 and provides 3 degrees of freedomfor manipulator 106. The manipulator 106 may be application-specific orpatient-specific. In one embodiment, the manipulator 1422 may be initself un. actuated base and coupled to an actuation module 1420 asdescribed earlier. The robotic device comprising base 1420 and linemanipulator 1422, and also representing 106, is coupled to thecontroller 1430 via line 1432. In one embodiment, line 1432 is ashielded multiconductor cable transmitting motor power from thecontroller to piezoelectric motors in the robotic device or manipulator1422 or 106 (not shown) and receiving encoder signals from the roboticdevice to the controller. In one embodiment, one or more breakout boardsare coupled to platform 1412 or robot base 1420 to distribute controland sensor signals. In an alternate embodiment, pneumatic or hydraulicpower may be transmitted via line 1432. Alternatively, line 1432 mayinclude fiber optic communications. In one embodiment, controller 1430,which also represents 104, is also coupled to imaging coil 1418 viacable 1434 for control of the imaging coil configuration. Controller1430 receives power via cable 1438 from the MRI scanner room. Power mayinclude AC electricity and a ground connection. Connection 1438 may alsoinclude pressurized fluid such as air or nitrogen. Controller 1430 iscommunicatively couple to workstation 1450 or 102 via cable or othercoupling 1440. Cable 1440 may be a fiber optic communication cable thatpasses through waveguide 1444 in the wall 1446 of the MRI scanner room1400. Workstation 1450 represents user workstation 102 and may belocated in the MRI console or control room 1452 as described earlier.

Although the invention has been decided with various embodiments, itshould be realized that this invention is also capable of further andother embodiments within the spirit and scope of the appended claims.

What is claimed is:
 1. A modular system for image guided assistedmedical procedure, the system comprising: a manipulator for a specificmedical procedure; a controller connected to said manipulator anddirecting at least one motion thereof, said controller also capable ofdirecting at least one other manipulator; an imaging device enablingvisualization of a tissue at said specific medical procedure; and acomputer connected to said imaging device and said controller, whereinthe computer collects and processes images from said imaging device andinstructs said controller to direct said manipulator.
 2. The system ofclaim 1, wherein said medical procedure is a surgical procedure.
 3. Thesystem of claim 2, wherein said surgical procedure is a deep brainstimulation procedure.
 4. The system of claim 2, wherein said surgicalprocedure is performed in the presence of an MRI scanner.
 5. The systemof claim 4, wherein at least part of the surgical procedure is performedwithin the MRI scanner.
 6. The system of claim 5, wherein interactivelyupdated MRI images are used to guide the image guided assisted system.7. A modular system for image guided robotic assisted medical procedure,the system comprising: a manipulator for performing a deep brainstimulation procedure; a controller connected to said manipulator anddirecting at least one motion thereof, said controller also capable ofdirecting at least one other manipulator; an imaging device enablingvisualization of a tissue at said deep brain stimulation procedure; anda computer connected to said imaging device and said controller, whereinthe computer collects and processes images from said imaging device andinstructs said controller to direct said manipulator.
 8. The system ofclaim 7, wherein the imaging device is an MRI scanner.
 9. The system ofclaim 8, wherein the manipulator is designed to operate in the MRIenvironment.
 10. The system of claim 9, wherein the manipulator isdesigned to operate with a minimal degradation of MRI image quality. 11.A method for image guided robotic assisted medical procedure, the methodcomprising: identifying an area of a body for a medical procedure;defining at least one motion of an instrument, said at least one motionbeing required for performing the medical procedure; assembling amanipulator adapted for said medical procedure, said assemblingcomprising identifying linkages for performing said at least one motion,and selecting actuators and sensors for connecting to said linkages forcontrolling movements thereof; and connecting said manipulator to acontroller capable of directing said manipulator, said controller alsocapable of directing at least one other manipulator.
 12. The method ofclaim 11, wherein the medical procedure is deep brain stimulation leadplacement.
 13. The method of claim 11, wherein the manipulatorencompasses an actuator module and an end effector.
 14. The method ofclaim 11, wherein at least part of the manipulator is applicationspecific.
 15. The method of claim 14, wherein at least part of themanipulator is patient specific.
 16. The method of claim 11, wherein themethod is designed to operate in an MRI scanner environment.